/Engine/Source/Editor/UnrealEd/Classes/Editor/EditorEngine.h
Creates a new Play in Editor instance (which may be in a new process if not running under one process. This reads the current session state to start the next instance needed.
virtual void CreateNewPlayInEditorInstance ( [FRequestPlaySessionParams](API\Editor\UnrealEd\FRequestPlaySessionParams) & InRequestParams, const bool bInDedicatedInstance, const EPlayNetMode InNetMode )